Oh, my GOD!

I usually check my schedule by the calendar in my room. According to that, I have to work today.

But, actually my schedule book was correct and I didn't have to work today. I have forgot matching the right schedule to my calendar in my room.
I believed my calendar and I woke up early this morning, took a train as usual, and arrived at a office by 10:00. But, it was at noon that I recognized today was my off day.
I couldn't get money for two hours...